In modern antenna and communication systems, particularly those involving microwave and millimeter waves, the steering of electromagnetic signals plays an important role in the transmission to, or interconnection of, various system elements, such as in satellite tracking systems. The properties and characteristics of physical surfaces associated with such signals, in turn, can affect the desired transmission or reflection of the signals.
For example, it has been known for decades that the electromagnetic properties of a metal surface can be changed by applying periodic corrugations to that surface, such as corrugated surfaces used in horn antennas to improve the radiation pattern. The corrugations are typically one-quarter wavelength thick, and serve as a resonant structure to transform a low-impedance metal surface into a high-impedance surface. This affects the reflection phase of the surface, and also the propagation of surface waves along it.
The same technique can also be applied to cylindrical structures such as wires. An example is shown in FIG. 1, which is adapted from FIG. 9.9a in Ramo et al.'s "Fields and Waves in Communication Electronics", published by John Wiley & Sons, Third Edition, 1994. The structure succeeds in suppressing the propagation of AC currents along the wire at the resonance frequency. However, the entire structure is greater than one-half wavelength thick, which can be problematic in size/weight constrained areas, such as for use in orbiting satellites.
Therefore, there exists a need for an effective device which can improve performance of wide range of microwave and millimeter wave antennas and structures useful in satellite tracking systems, while being small in size and manufacturable at relatively low cost. The present invention provides a unique solution to meet such need.